<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			* {
				margin: 0;
				padding: 0;
			}

			#test {
				width: 200px;
				height: 200px;
				background: pink;
				/*这个一定要看mdn*/
				margin: auto;
				/*垂直居中*/
				text-align: center;
				line-height: 200px;
			}
		</style>
	</head>
	<body>
		<div id="test">
			test
		</div>
	</body>
</html>
